This invention relates to a method for the treatment of used lubricating oils to obtain a purified oil product. This invention also relates to the removal of contaminants from used lubricating oil by a series of treatments of the used lubricating oil. In another aspect this invention relates to the process of producing a finished oil from a demetallized used oil without the use of hydrogen.
The large rise in crude prices of recent years has increased the interest in reclaiming used lubricating oils and with the ever-decreasing petroleum reserves, it becomes more and more essential that this used oil be saved and reused.
Also in recent years more and more additives have been employed in petroleum lubricating oils, the economic removal of these additives and impurities formed in used lubricating oils, so that the oil may be reused, has proven to be no small task.
Materials contained in a typical used crankcase oil that are undesirable if the oil is to be reused include sub-micron size carbon particles, atmospheric dust, metal and metal particles, detergents, pour point depressants, oxidation inhibitors, viscosity index improvers and resins. Besides lead, which is generally present at concentrations of 1 to 2.5 weight percent, appreciable amounts of zinc, barium, calcium, phosphorus and iron are also present in the used crankcase oil.
Recently, a technique of purifying used oil has been developed in which the used oil is reacted with an aqueous solution of an ammonium salt treating agent, then the water and light hydrocarbons are removed as vapor, the resulting oil phase-containing mass is separated by filtration, then an adsorbant to remove gum forming contaminants is added, and the resulting oil is hydrotreated by contacting it with hydrogen and a hydrotreating catalyst. Such a technique is described in U.S. Pat. No. 4,151,072 the disclosure of which is incorporated herein by reference. This process is satisfactory for most industrialized locations, but there are areas where hydrogen is either expensive or unavailable making it uneconomical to reclaim used lubricating oil in these areas.
It is an object of this invention to provide an improvement on the method disclosed in U.S. Pat. No. 4,151,072.
Another object of this invention is to produce a finished oil from a demetallized used oil without the use of hydrogen.
Another object of this invention is to provide a process for reclaiming a high purity lube oil stock from used lubricating oils.
A further object of this invention is to provide an improved process for removing both additives and solid contaminants from used lubricating oils.
Other aspects, objects, as well as the advantages of this invention will become apparent to one skilled in the art upon a study of the specification, the appended claims, and the drawings.